1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copying machine, a facsimile device, and a printer. More particularly, the present invention relates to a development device installed in such image forming apparatus, and a process cartridge having the development device.
2. Description of the Related Art
In a development device in which developer is circulated and conveyed between a first chamber and a second chamber by two rotary conveying bodies, the developer that is conveyed from an upstream applies, to a downstream developer, force parallel to the direction of travel of the developer, and then the downstream developer is pushed toward a downstream in order to eliminate the pressure caused by the application of the force, whereby the developer, which is positioned in a location where the rotary conveying body does not directly passes through, is moved. In the vicinity of the bearing of the rotary conveying body, the direction of the pressure that the downstream developer receives from the upstream developer is substantially perpendicular to the direction of the movement of the downstream developer, and the flow of the developer is extremely worse at a corner of an internal wall, compared to other positions, thus the developer is accumulated easily.
Furthermore, there are the following two problems in accumulation of the developer at the corner of the internal wall.
(1) The temperature in the vicinity of the bearing of the rotary conveying body is higher than that of the peripheral area because of sliding heat, and the accumulated developer continuously receives pressure from the developer conveyed from the upstream, causing a problem such as developer aggregation.
(2) Even if the developer is not accumulated completely, the developer in the vicinity of the corner of the internal wall does not move easily, compared to the developer located in other position, thus such developer is not stirred sufficiently, whereby the uniformity of the toner density and charging volume in the entire developer is deteriorated.
Therefore, in order to solve these problems, there is known a development device disclosed in, for example, Japanese Unexamined Patent Publication No. 2006-003524. However, as will be described hereinafter with reference to the drawings, there is a problem that the size of the development device is large, causing increase in the production cause.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Unexamined Patent Publication No. H10-339991 and Japanese Unexamined Patent Publication No. H11-024382.